Narrowband Terahertz Imager for Nonmelanoma Skin Cancer Detection Terahertz (THz) radiation is nonionizing and safe for probing human tissue. Unlike ultrasound, THz light is capable of submillimeter resolution and, unlike other imaging techniques, THz light is not affected by light scattering. This unique capability has given rise to a number of potential applications for THz light in medicine and bioscience. Realization of these applications has been hampered because existing THz sources generally have low output power, some have limited tunability, and many emit broadband radiation, which can be unsuitable for certain applications. Researchers at the University of California at Los Angeles (UCLA) have demonstrated a new scheme for generating powerful, narrowband, and tunable THz light that can satisfy the needs of these applications. In order to develop this scheme into a practical technology, we are proposing to focus on one specific, highly promising application - an imaging system for detection of basal cell carcinoma (BCC). Nonmelanoma skin cancer is the most prevalent form of cancer affecting over 1 million people per year. Preclinical tests have shown the ability to detect BCC with THz light because BCC tissue tends to have higher water content than normal tissue and THz light is strongly absorbed by water. However, current THz-based diagnostics rely on relatively weak broadband THz sources and require many minutes to create an image of the skin via raster scanning. During scanning the affected skin area must be pressed against a quartz plate, which precludes diagnosing the face and neck. False-positive results are also possible because inflamed normal tissue adjacent to the BCC can strongly absorb THz light. Hence, a more discriminating, more rapid, and noncontact THz-based diagnostic is needed. The overall goal of our program is to develop a narrowband, high-peak-power THz imaging system based upon the UCLA work that 1) is powerful enough to obtain 2-D images without the need for raster scanning with the specimen placed on a quartz plate;and 2) will use its narrowband capability to enable unambiguous detection of the carcinoma in a manner that is not possible with a broadband THz source. During Phase I, we will utilize the UCLA THz source, which has limited tunability, to perform proof-of- principle experiments to demonstrate THz imaging of water phantoms. During Phase II, a higher average power and highly tunable narrowband THz source will be built and used to demonstrate improved detection of BCC. Medical research collaborators will be involved during the Phase II tests. PUBLIC HEALTH RELEVANCE: Narrowband Terahertz Imager for Nonmelanoma Skin Cancer Detection Nonmelanoma skin cancer is the most prevalent form of cancer affecting over 1 million people per year. A new type of skin cancer diagnostic is being developed that will make it easier to identify cancerous tissue and will aid the surgeon during removal of the skin cancer to ensure all the cancer is excised while minimizing removal of healthy tissue. This diagnostic will also be useful as a new tool for medical and bioscience research.